Browsing by Author "Onal, Ahmet M."

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Donor-Acceptor Polymer Electrochromes With Cyan Color: Effect of Alkyl Chain Length on Doping Processes
(Elsevier, 2012) Celikbilek, Ozden; Icli-Ozkut, Merve; Algi, Fatih; Onal, Ahmet M.; Cihaner, Atilla
A new series of donor-acceptor-donor (D-A-D) type compounds consisting of dialkyl substituted 3,4-propylenedioxythiophene and benzothiadiazole units were synthesized and polymerized chemically and electrochemically to investigate the effect of alkyl chain length on the doping process of the conjugated polymers. It was found that the alkyl chain length plays a key role on both doping processes and the solubility of the polymer. It is also noteworthy that this new series of D-A-D electrochromes transmits or reflects the cyan color of the Cyan-Magenta-Yellow (CMY) color space in the neutral state which can be switched to transmissive grey when oxidized. (C) 2011 Elsevier B.V. All rights reserved.
Furan and Benzochalcogenodiazole Based Multichromic Polymers Via a Donor-Acceptor Approach
(Royal Soc Chemistry, 2013) Icli-Ozkut, Merve; Ipek, Halil; Karabay, Baris; Cihaner, Atilla; Onal, Ahmet M.
Two new furan and benzochalcogenodiazole based monomers, namely 4,7-di(furan-2-yl) benzo[c][1,2,5]-selenadiazole (FSeF) and 4,7-di(furan-2-yl) benzo[c][1,2,5]thiadiazole (FSF), were designed and synthesized via a donor-acceptor-donor approach. The monomers were electrochemically polymerized via potentiodynamic or potentiostatic methods. The monomers and their polymers exhibited lower oxidation potentials (1.16 V and 1.06 V for monomers; 0.93 V and 0.80 V for polymers vs. Ag/AgCl) and red shifts of the whole dual-band absorption spectra upon moving from S to Se. Intramolecular charge transfer properties of the monomers and the polymers were demonstrated by using electroanalytical and optical methods. Also, the polymers PFSeF and PFSF were multicolored at different redox states and have low band gaps of 1.43 eV and 1.61 eV, respectively.
Members of Cmy Color Space: Cyan and Magenta Colored Polymers Based on Oxadiazole Acceptor Unit
(Amer Chemical Soc, 2012) Ozkut, Merve Icli; Algi, Melek Pamuk; Oztas, Zahide; Algi, Fatih; Onal, Ahmet M.; Cihaner, Atilla
In this study, three novel oxadiazole-based polymers were synthesized and their electrochemical and optical properties were investigated. The polymers were found to have both p- and n-type doping properties accompanied by electrochromic response. Two polymer films exhibit cyan and magenta colors, which constitute two legs of CMY color spaces, in their neutral states and they are soluble in common-organic solvents. According to the color mixing theory, all colors in the visible spectrum including black color can be obtained by using these polymers with a yellow colored electrochromic polymer. Among these polymers, the polymer bearing propyledioxythiophene donor units has some superior properties like high stability (it retains 94% of its electroactivity after 2000 cycles), solubility, and high coloration efficiency (230 cm(2)/C), whereas as expected ethylenedioxythiophene containing one has the lowest band gap as 1.08 eV.
Substituent and Heteroatom Effects on the Electrochromic Properties of Similar Systems
(Wiley-blackwell, 2012) Icli-Ozkut, Merve; Mersini, Jetmire; Onal, Ahmet M.; Cihaner, Atilla
Electrochromic polymers called poly(3,4-dihydro-3,3-bis ((naphthalen-1-yl)methyl)-2H-thieno[3,4-b][1,4]dioxepine) (PProDOT-Np-2), poly(3,3-dibenzyl-3,4-dihydro-2H-selenopheno[3,4-b][1,4]dioxepine), and poly(3,3-dibenzyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine) were synthesized electrochemically and the effect of substituents and heteroatoms on the electrochromic properties were investigated for the similar systems. All polymers show electrochromism from a colored state when neutralized to transmissive when oxidized. Although, increasing bulky size (PProDOT-Np-2) causes lower coloration efficiency (CE) as well as lower optical contrast, the replacement of S atom by Se atom resulted in a lower band gap polymer with a higher CE than its thiophene analog. (c) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 615- 621, 2012
Synthesis and Electropolymerization of a New Ion Sensitive Ethylenedioxy-Substituted Terthiophene Monomer Bearing a Quinoxaline Moiety
(Elsevier Science Sa, 2012) Carbas, Buket Bezgin; Kivrak, Arif; Zora, Metin; Onal, Ahmet M.
A new terthienyl based fluorescent polymer bearing pendant quinoxaline moieties directly attached to the 3-positions of the central thiophene ring was synthesized by electrochemical polymerization of 4-(2,5-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)thiophen-3-yl)Pyrrolo[1,2-a]quinoxaline (EE-Q). The corresponding polymer, poly(4-(2,5-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)thiophen-3-yl)pyrrolo[1,2-a]quinoxaline) P(EE-Q), was characterized by cyclic voltammetry, FT-IR and UV-vis spectroscopy. The polymer exhibits a reversible redox behaviour (E-p(1/2) = 0.75 V) accompanied with a reversible electrochromic behavior; brownish red in the neutral state and green in the oxidized state. The band gap value for the polymer was found to be 1.75 eV. Moreover, the sensitivity of both the monomer and its polymer towards metal cations was investigated by monitoring the change in the fluorescence intensity. Among various common ions, both the monomer and its polymer were found to be selective towards Fe3+ ions by quenching the fluorescence efficiency with a Stern-Volmer constant (K-SV) of (1.9 x 10(3) M-1) and (5.0 x 10(2) M-1) for monomer and polymer solutions, respectively. (C) 2012 Elsevier B.V. All rights reserved.
Synthesis and Electropolymerization of an Ion Sensing and Fluorescent Fluorene Derivative Bearing a Quinoxaline Moiety and Its Analogues With Different Donor Units
(Elsevier, 2012) Kivrak, Arif; Carbas, Buket Bezgin; Zora, Metin; Onal, Ahmet M.
A series of new fluorene derivatives bearing pendant quinoxaline moieties with different donor groups, namely 5'H-spiro[fluorene-9,4'-pyrrolo[1,2-alquinoxaline] (FQ), 2,7-di(thiophen-2-yl)-5'H-spiro[fluorene-9,4'-pyrrolo[1,2-a]quinoxaline] (TQT), 2,7-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-5'H-spiro[fluorene-9,4'-pyrrolo[1,2-a]quinoxaline] (EQE) and 2,7-bis(3,3-dihexyl-3,4-dihydro-2H-thieno[3,4-b][1,4)dioxepin-6-yl)-5'H-spiro[fluorene-9,4'-pyrrolo[1,2-a]quinoxaline] (PQP) were synthesized. The monomers were electropolymerized via potentiodynamic methods in order to understand the effects of donor units on the electrochemical and optoelectronic properties of the resulting polymers. It was found that polymer films exhibit reversible redox behavior accompanied with a reversible electrochromic behavior (E-p(ox) = 0.95 V for poly(2,7-di(thiophen-2-yl)-5'H-spiro[fluorene-9,4'-pyrrolo[1,2-a]quinoxaline]) (PTQT), E-p(ox) = 0.90 V for poly(2,7-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-5'H-spiro[fluorene-9,4'-pyrrolo[1,2-a]quinoxaline]) (PEQE) and E-p(ox) = 0.67 V for poly(2,7-bis(3,3-dihexyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin-6-yl)-5'H-spiro[fluorene-9,4'-pyrrolo[1,2 a]quinoxaline]) (PPQP)). The band gap values (E-g) of the polymers were found to be 2.47, 1.93 and 1.66 eV for PTQT, PEQE and PPQP, respectively. Furthermore, the ion sensitivity of PQP and its polymer PPQP was also investigated by monitoring the change in the fluorescence intensity. Among various common ions, both PQP and PPQP were found to be selective towards Fe2+ ions by quenching the fluorescence efficiency with a Stern-Volmer constant (K-sv) of (5.9 x 10(3) M-1) and (2.7 x 10(4) M-1) for monomer and polymer solutions, respectively. (C) 2012 Elsevier Ltd. All rights reserved.